The following patents and/or commonly assigned patent applications are hereby incorporated herein by reference:
This invention relates to the field of mechanical assembly, more particularly to the alignment and attachment of image displays, particularly spatial light modulators.
Many display systems use multiple spatial light modulators, such as liquid crystal display panels (LCDs) or digital micro mirror devices (DMDTM) to create a single full-color image. Generally a white light source is used to create a white light beam that is split, using dichroic filters, into three primary color light beams. Each primary color light beam is incident on a separate modulator and the three modulated primary color light beams are recombined to form a single full-color image bearing beam of light.
Precise alignment of the three modulators is critical to achieving a high-quality image. Current DMD-based systems use adjustable sockets. The DMDs are mounted in the sockets and a six-axis alignment is performed using the adjustment screws provided by the socket The six axes corresponding to the six degrees of freedom, three rectangular and three rotational. After each DMD is aligned, the adjustment hardware locked down using thick epoxy bonds. Unfortunately, the high illumination levels experienced by the modulations in many image projectors results in a very high operating temperature. Furthermore, the operating temperature is rarely uniform from one modulator to the next, or even from one portion of a given modulator to another portion. Both the adjustment hardware and the thick epoxy bonds holding the adjustment hardware in place tend to expand and contract a great deal over the temperature extremes, allowing the convergence to drift over time and temperature. Typical display systems require alignment to within one-half pixel. Since DMI)s have a pixel size of 17 xcexcm or less, this requires long-term alignment to within 8.51xcexcm.
A new method of attaching and aligning modulators is needed. An acceptable method and apparatus should enable easy alignment of the modulators and be able to maintain this alignment over long periods of extreme temperature variations.
Objects and advantages will be obvious, and will in part appear hereinafter and will be accomplished by the present invention that provides a method and system for a six-axis attachment method and apparatus for spatial light modulators. One embodiment of the claimed invention provides an attachment mechanism capable of maintaining the alignment of a spatial light modulator in six axes. The mechanism comprises: at least one pin, a socket plate, a modulator, and a washer. The modulator is attached to the socket plate which has clearance holes to accept the pin. The washer slides over the pin and is bonded to the socket plate and the pin. Typically four pins are used, and are held by an attachment plate. The washer is typically transparent to allow the use of an optically curable adhesive. During the adhesive cure process, light shines through the washer and cures the optically curable adhesive. An alternative embodiment envisions a combined modulator and socket plate wherein the socket plate and clearance holes are an integral part of the modulator. While the attachment structure and method is described herein with respect to the attachment of a DMD to a prism, it can be used in virtually any application requiring a strong, stable attachment.
The disclosed attachment method and system provides a strong, reliable bond that is adjustable prior to adhesive cure. Because a minimal amount of adhesive is used, the bond tends to hold its position during and after the cure.